Evaluation of native plant seeds and seeding in the east-side central Cascades ponderosa pine zone.

Abstract

Vance, Nan C. 2010. Evaluation of native plant seeds and seeding in the east-side central Cascades ponderosa pine zone. Gen. Tech. Rep. PNW-GTR-823. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 85 p. In dry, open coniferous forests of the montane West, stand-replacing wildfires and land use activities alter the composition and abundance of native grasses and forbs by degrading the habitat and accelerating the invasion of exotic annuals. On these lands, native forbs and grasses delayed or prevented from recovery by natural processes may require intervention through supplementary seeding. However, effective seeding of native plants requires that their seed traits and the potential outcome of the seeding be better understood. This study evaluated seeds and seedlings of 13 native forbs and 5 grasses common in the dry Pinus ponderosa/Purshia tridentata/ Festuca idahoensis plant communities east of the Oregon Cascades crest and their potential for establishment in a landscape altered by past grazing and a recent, stand-replacing wildfire. Their potential for germination and establishment was examined in the laboratory and in 20 test plots located within the burned boundary of a 2002 wildfire. Seed collection, handling, testing, and sowing procedures are described. Data on seedling emergence, height, second-year survival and cover are presented in tables and figures. Onsite emergence and early growth data helped to reveal cause of early mortality related to biological and site conditions, including invasive competition, and differences in early growth and site occupancy. The study supports the efficacy of using multiple and functionally diverse species in a seeding program. Additional information on each of the 18 species is included in an appendix.